U.S. patent number 10,573,924 [Application Number 15/623,438] was granted by the patent office on 2020-02-25 for electrochemical cell.
This patent grant is currently assigned to VARTA Microbattery GmbH. The grantee listed for this patent is VARTA Microbattery GmbH. Invention is credited to Rolf Brenner, Juergen Ernsperger, Claus-Christian Fischer, Winfried Gaugler, Rainer Hald, Goran Kilibarda, Bernd Kreidler.
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United States Patent |
10,573,924 |
Brenner , et al. |
February 25, 2020 |
Electrochemical cell
Abstract
An electrochemical cell includes a composite electrode body with
at least one positive and at least one negative electrode; an
electrolyte that impregnates the composite electrode body; and a
housing with a liquid-impervious interior, wherein the composite
electrode body impregnated with the electrolyte is disposed in the
interior, and the housing consists of PEK or a PEK based
material.
Inventors: |
Brenner; Rolf (Ellwangen Jagst,
DE), Ernsperger; Juergen (Neuler, DE),
Fischer; Claus-Christian (Ellwangen Jagst, DE),
Gaugler; Winfried (Ellwangen Jagst, DE), Hald;
Rainer (Ellwangen Jagst, DE), Kilibarda; Goran
(Schwaebisch Gmuend, DE), Kreidler; Bernd (Ellwangen
Jagst, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
VARTA Microbattery GmbH |
Ellwangen Jagst |
N/A |
DE |
|
|
Assignee: |
VARTA Microbattery GmbH
(Ellwangen Jagst, DE)
|
Family
ID: |
56550774 |
Appl.
No.: |
15/623,438 |
Filed: |
June 15, 2017 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20180069261 A1 |
Mar 8, 2018 |
|
Foreign Application Priority Data
|
|
|
|
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Jul 26, 2016 [EP] |
|
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16181222 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
2/0222 (20130101); H01M 2/022 (20130101); H01M
2/0277 (20130101); C08G 65/4012 (20130101); H01M
10/056 (20130101); H01M 10/0525 (20130101); H01M
4/045 (20130101); H01M 2/0404 (20130101); H01M
2/0465 (20130101); H01M 2/0482 (20130101); H01M
10/0587 (20130101); H01M 2/046 (20130101) |
Current International
Class: |
H01M
10/0525 (20100101); C08G 65/40 (20060101); H01M
2/04 (20060101); H01M 2/02 (20060101); H01M
10/056 (20100101); H01M 4/04 (20060101); H01M
10/0587 (20100101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
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1945890 |
|
Apr 2007 |
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CN |
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201918433 |
|
Aug 2011 |
|
CN |
|
2 367 218 |
|
Sep 2011 |
|
EP |
|
2004-6157 |
|
Jan 2004 |
|
JP |
|
2010-113963 |
|
May 2010 |
|
JP |
|
2010/089152 |
|
Aug 2010 |
|
WO |
|
2010/146154 |
|
Dec 2010 |
|
WO |
|
Other References
European Search Report dated Sep. 22, 2016 in corresponding
European Patent Application No. 16181222.7. cited by applicant
.
First Office Action dated May 13, 2019 of counterpart Chinese
Application No. 201710617186.9, along with an English translation.
cited by applicant.
|
Primary Examiner: Chandler; Kaity V
Attorney, Agent or Firm: DLA Piper LLP (US)
Claims
The invention claimed is:
1. An electrochemical cell comprising: a ring-shaped composite
electrode body with at least one positive and at least one negative
electrode and comprising at least one output conductor electrically
connected to the at least one positive electrode of the composite
electrode body and at least one output conductor electrically
connected to the at least one negative electrode of the composite
electrode body; an electrolyte that impregnates the ring-shaped
composite electrode body; and a ring-shaped housing with a
ring-shaped liquid-impervious interior, wherein the ring-shaped
composite electrode body impregnated with the electrolyte is
disposed in the interior, the composite electrode body is
ring-shaped, the ring-shaped housing has an exterior wall
comprising an outer circumferential wall and a concentrically
arranged inner circumferential wall, wherein the inner
circumferential wall of the exterior wall defines a central
through-hole or recess around which the ring-shaped interior of the
housing is arranged, the ring-shaped composite electrode body is
arranged within the ring-shaped interior, the housing comprises two
housing parts that together form the interior of the housing, the
two housing parts consist of PEK films, the housing parts are
joined to one another via at least one welded or bonded seam, and
the output conductors are guided outwardly of the housing between
the two housing parts.
2. The cell according to claim 1, wherein: the PEK films have a
thickness of 50 .mu.m to 500 .mu.m.
3. The cell according to claim 1, comprising at least one of: a.
the ring-shaped housing has at least two spatially separated welded
or bonded seams; and b. the bonded or welded seams each have a
ring-shaped profile.
4. The cell according to claim 1, comprising at least one of: a.
the central through-hole or recess has a cylindrical geometry; b.
the ring-shaped housing comprises two circular ring-shaped housing
ends spaced apart from one another and parallel to one another, and
a ring-shaped inner housing shell that connects the housing ends
and a ring-shaped outer housing shell that connects the housing
ends, with each of the housing shells and each of the housing ends
having an inside that points into the interior and an outside that
points in the opposite direction; and c. the ring-shaped composite
electrode body is a hollow cylindrical winding formed from
electrode tapes and at least one separator tape, and has end faces
that are formed by longitudinal edges of the electrode tapes, in
the center of which there is an axial hollow cavity having openings
in the center of the end faces.
5. The cell according to claim 1, comprising at least one of: a.
the cell is a lithium ion cell; b. at least one of the electrodes
of the ring-shaped composite electrode body is a
lithium-intercalating electrode; and c. the ring-shaped composite
electrode body has been impregnated with an organic electrolyte
with a conductive lithium salt dissolved therein.
Description
TECHNICAL FIELD
This disclosure relates to an electrochemical cell.
BACKGROUND
Particularly well-known examples of electrochemical cells are
button cells and round cells. Button cells usually have a
cylindrical housing, the height of which is equal to or less than
its diameter. In round cells, the housing is likewise cylindrical,
but its height exceeds its diameter.
It is possible for very different electrochemical systems to be
present in the housings. Very widespread cells are those based on
zinc/air, zinc/MnO.sub.2 and nickel/zinc. Secondary (rechargeable)
systems are also widespread. Examples of these are nickel/metal
hydride cells, nickel/cadmium cells and lithium ion cells.
The cylindrical housing of round cells and button cells
conventionally consists, in general, of two solid, usually metallic
housing parts, between which there is arranged an electrically
insulating seal. One of the housing parts electrically connects to
the positive electrode and has correspondingly positive polarity.
The other electrically connects to the negative electrode and has
correspondingly negative polarity. The seal is intended to prevent
electrical contact between the housing parts having opposite
polarity. Furthermore, it is intended to counteract escape of
liquid and moisture from the housing and penetration thereof into
the housing.
The use of metallic housings is associated with various
disadvantages. They are produced by a complex deep drawing method,
and corrosive attack on the housing by the electrolyte or by other
corrosive substances formed in the charging and discharging
operation can never be entirely ruled out in spite of specific
precautions.
SUMMARY
We provide an electrochemical cell including a composite electrode
body with at least one positive and at least one negative
electrode; an electrolyte that impregnates the composite electrode
body; and a housing with a liquid-impervious interior, wherein the
composite electrode body impregnated with the electrolyte is
disposed in the interior, and the housing consists of PEK or a PEK
based material.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a schematic cross-sectional view of an electrochemical
cell.
FIGS. 1B and 1C are schematic cross-sectional views of housing
parts.
FIG. 1D is a schematic top plan view of a housing part and a
composite electrode body.
FIG. 1E is a schematic cross-sectional view of the structure of
FIG. 1D taken through line S.
DETAILED DESCRIPTION
It will be appreciated that the following description is intended
to refer to specific examples of structure selected for
illustration in the drawings and is not intended to define or limit
the disclosure, other than in the appended claims.
We provide an electrochemical cell that includes the following
features: It comprises a composite electrode body having at least
one positive and at least one negative electrode: in such a
composite body, the at least one positive electrode and the at
least one negative electrode are bonded to one another in a fixed
manner, usually via lamination or adhesive bonding. There is
usually a separator arranged between electrodes of opposite
polarity, which may be a porous polymer film, for example, of a
polyolefin. Wound composite electrode bodies are known. Button
cells having wound composite electrode bodies are described, for
example, in WO 2010/146154 A2 and in WO 2010/089152 A1. The
composite electrode bodies described therein can also be used as a
cell herein. For production of such wound composite electrode
bodies, a single cell in tape form is produced in a first step. For
this purpose, positive electrodes in tape form and negative
electrodes in tape form are combined with one another and with one
or more separators in tape form. The electrodes can, for example,
be laminated on opposite sides of a separator. The single cell in
tape form thus produced is then fed to a winding apparatus and
processed therein to give the wound composite electrode body. For
this purpose, the single cell is typically wound on a winding
spindle or a winding core. After a usually predefined number of
windings (a winding is understood here to mean each complete
revolution of the composite around the winding spindle or winding
core), the winding operation is stopped. The wound composite body
formed is separated, for example, by a cutting or punching tool,
from the immediately following, as yet unwound section of the
single cell. The composite electrode body has been impregnated with
an electrolyte: the choice of electrolyte depends on which
electrochemical system is being chosen for the cell. If the cell is
a nickel/metal hydride cell, the electrolyte is an alkali. If the
cell is a lithium ion cell, the electrolyte is generally composed
of a mixture of organic carbonates with a conductive lithium salt
dissolved therein. It comprises a housing with a liquid-impervious
interior: as in conventional cells, the primary function of the
housing is to prevent escape of liquid (electrolyte) from the
housing and penetration of moisture out of and into the housing.
The composite electrode body impregnated with the electrolyte is
disposed in the interior: the aim is generally for the composite
electrode body to fill the interior with maximum efficiency. Any
dead volume in the interior has an adverse effect on the energy
density.
It is a particular feature that the housing consists of PEK
(polyether ketone) or a PEK based material. As is well known,
polyether ketones are thermoplastics of high thermal stability. The
most commonly used polyether ketones are polyaryl ether ketones
(PAEK for short). One of the most well-known and important
representatives of PEKs is PEEK (polyether ether ketone). More
preferably, the housing of the cell consists of PEEK or a PEEK
based material.
A PEK based material consists at least partially of PEK. Similarly,
a PEEK based material is a material consisting of at least
partially of PEEK. A PEK or PEEK based material may contain (in
addition to PEK or PEEK) other components, for example, inorganic
or organic fillers and/or pigments. However, it is preferred that
PEK or PEEK is always present in the materials in an amount of at
least 20% by weight. Preferably PEK or PEEK are the main components
of the PEK/PEEK based materials.
The melting temperature of PEEK is about 335.degree. C. to
345.degree. C. There are various derivatives (e.g., PEEEK
(poly(ether ether ether ketone)) and PEKK (poly(ether ketone
ketone))), which have slightly different melting points (e.g., PEKK
about 391.degree. C. or PEEEK about 324.degree. C.). All these
derivatives are suitable as housing materials for the cell.
Polyether ketones are stable to almost all organic and inorganic
chemicals. They are sensitive only to UV radiation and to strongly
acidic and oxidizing conditions, but these are generally not
encountered in batteries.
The use of PEK as housing material brings various advantages. Being
a thermoplastic, PEK is very much easier to process and form than
metallic materials. It is very substantially inert with respect to
corrosive substances that are customary in electrochemical cells.
Being an electrical insulator, it minimizes the opportunities for
short circuits across the housing. Furthermore, it has a very much
lower density than metallic housing materials. Given the same
housing thickness, the use of PEK gives rise to distinct weight
advantages.
It is preferable that the cell is notable for at least one of the
following additional features: Preferably, the housing comprises
two housing parts together forming the interior of the housing. The
two housing parts preferably consist of PEEK films. These
preferably have a thickness of 50 .mu.m to 500 .mu.m. Within this
range, preference is further given to a thickness of 100 .mu.m to
300 .mu.m. The housing parts can be bonded to one another by an
adhesive or else by welding. Correspondingly, the housing parts, in
preferred examples, are joined to one another via at least one
welded or bonded seam. Joining of the housing parts by welding is
preferable in principle. Housing parts, especially housing films,
of PEK can be welded to one another without difficulty, for
example, by a laser. Thermoplastics such as PEK absorb just a small
proportion of the laser radiation from solid-state lasers in their
standard wavelength ranges of 800 to 1100 nm. So that these
thermoplastics can be efficiently melted and welded by a laser
radiation, it is possible to add additives that improve the
absorption properties thereof. Suitable for this purpose are all
inorganic or organic color pigments that absorb the radiation from
solid-state lasers within the stated wavelength range, for example,
carbon black. The housing parts can be bonded, for example, by a
hotmelt adhesive or a chemically setting adhesive. Suitable
examples are polyimide adhesive tapes, polyethylene or
polypropylene sealing films, epoxy resin or polyurethane.
Further preferably, the composite electrode body comprises: at
least one output conductor electrically connected to the at least
one positive electrode of the composite electrode body and/or at
least one output conductor electrically connected to the at least
one negative electrode of the composite electrode body.
Preferably, the output conductor(s) is/are guided out of the
interior of the housing to the outside, especially between the two
housing parts.
Particularly preferably, the housing has at least two spatially
separate welded or bonded seams, it being preferable that the
welded or bonded seams each have a ring-shaped profile.
This is especially when the cell has at least one of the following
additional features: When the above-described composite electrode
body is ring-shaped. When the liquid-impervious interior is
ring-shaped and arranged around a central through-hole or recess.
When the ring-shaped composite electrode body is arranged within
the ring-shaped interior. Housings of conventional round cells and
button cells are cylindrical. They do not have a central
through-hole or recess.
As described at the outset, the cylindrical housing of round cells
and button cells generally consists of two solid, usually metallic
housing parts, between which there is arranged an electrically
insulating seal. These cells always have exactly one seal region.
The situation is different in the latter example of cells. As a
result of the presence of the central through-hole or the recess,
these cells generally have two or more seal regions. It may thus
also be the case that more than one seal is required to seal the
cell.
In all examples with the central through-hole or recess, the
housing of the cell includes either the through-hole or the recess.
The central through-hole is always continuous and, hence,
penetrates the housing from one side to the other side and is
correspondingly accessible from two sides of the housing. The
recess, by contrast, is not continuous. It is accessible only from
one side of the housing.
Particularly preferably, the cell has at least one of the following
additional features: The housing takes the form of a hollow
cylinder. The central through-hole or the recess has cylindrical
geometry. The housing comprises two circular ring-shaped housing
ends spaced apart from one another and parallel to one another, and
a ring-shaped inner housing shell that connects the housing ends
and a ring-shaped outer housing shell that connects the housing
ends, with each of the housing shells and each of the housing ends
having an inside that points into the interior and an outside that
points in the opposite direction. The composite electrode body
takes the form of a hollow cylindrical winding formed from
electrode tapes and at least one separator tape, and has end faces
formed by longitudinal edges of the electrode tapes, in the center
of which there is an axial hollow cavity having openings in the
center of the end faces.
To achieve the best exploitation of capacity, it is appropriate to
match the geometric features of the ring-shaped composite electrode
body and of the ring-shaped liquid-impervious housing to one
another as well as possible. The composite electrode bodies such as
those described, for example, in FIG. 3a and FIG. 3b of WO
2010/089152 A1 are virtually perfect hollow cylinders. These can
best exploit the volume of the ring-shaped interior when the
interior is likewise in the form of a hollow cylinder.
The through-hole preferably takes the form of a continuous
cylindrical hole. The recess preferably takes the form of a
cylindrical hole closed at one end.
Preferably, our cell is characterized by at least one of the
following additional features: The cell is a lithium ion cell,
especially a secondary lithium ion cell. At least one of the
electrodes of the composite electrode body is a
lithium-intercalating electrode. The composite electrode body has
been impregnated with an organic electrolyte with a conductive
lithium salt dissolved therein.
The electrodes of a lithium ion cell typically comprise
electrochemically active components and electrochemically inactive
components.
Useful electrochemically active components (often also referred to
as active materials) for secondary lithium ion systems are all
materials that can absorb lithium ions and release them again. The
state of the art in this regard for the negative electrode is
especially carbon-based materials such as graphitic carbon, or
non-graphitic carbon materials that are capable of intercalating
lithium. In addition, it is also possible to use metallic and
semi-metallic materials that can be alloyed with lithium, or
composites of such materials with carbon-based materials. Useful
materials for the positive electrode especially include
lithium-metal oxide compounds and lithium-metal phosphate compounds
such as LiCoO.sub.2 and LiFePO.sub.4.
Electrochemically inactive components primarily include electrode
binders and current collectors. The latter serve to form electrical
contact over a maximum area with the electrochemically active
components. They typically consist of flat metal substrates, for
example, metal foils or a metal foam or a metallized nonwoven. The
electrode binders ensure the mechanical stability of the electrodes
and assure contacting of the particles of electrochemically active
material with one another and the current collector. In addition,
the term especially also covers conductors, i.e., carbon black, for
example.
Conduction of electrons to and away from the electrodes of the
composite electrode body is usually via output conductor lugs that
can project, for example, beyond the ends of the wound composite
body formed. The output conductor lugs are electrically connected
to or are part of the current collectors.
The electrochemical cell is in principle not subject to any
restriction in terms of its size, including the ratios of the
diameters (external diameter/internal diameter) or their height. In
some examples in which the housing takes the form of a hollow
cylinder, it is preferable, however, that their height exceeds
their external diameter by a factor of not more than 2. The
height/external diameter ratio may be .ltoreq.1.
Further features and advantages that result therefrom will be
apparent from the drawings and from the description of the drawings
which follows. The examples described hereinafter serve merely for
illustration and better understanding and should in no way be
regarded as a restriction.
FIG. 1A shows one example of an electrochemical cell 100 (schematic
cross-sectional diagram). This comprises a ring-shaped composite
electrode body 101 and a housing 102 consisting of the housing
parts 102a and 102b. The housing parts 102a and 102b are
additionally shown separately (FIGS. 1B and 1C, schematic
cross-sectional diagram). In addition, FIG. 1D (schematic diagram,
top view) and 1E (schematic cross-sectional diagram, section
through line S) show the housing part 102a and a composite
electrode body 101 used therein.
The ring-shaped composite electrode body 101 is a lithium ion cell
impregnated with an organic electrolyte. The composite electrode
body 101 takes the form of a hollow cylindrical winding formed from
electrode tapes and at least one separator tape, the end faces 101a
and 101b of which are formed by longitudinal edges of the electrode
tapes.
The housing parts 102a and 102b each consist of a PEEK film having
a thickness between 100 and 150 .mu.m. The housing part 102a has
two recesses formed by deep drawing, a central cylindrical recess
103 and an outer hollow cylindrical recess 104. The housing part
102b is in the form of a dish.
The housing parts 102a and 102b are joined to one another via the
two ring-shaped weld seams 105 and 106. Together they enclose the
ring-shaped interior 107 that encloses the composite electrode body
101 in a liquid-impervious manner. The interior 107 is in turn
arranged around the recess 103.
The composite electrode body 101 comprises two output conductors
108 and 109 that are electrically connected to one positive and one
negative electrode of the composite electrode body 101. The output
conductors 108 and 109 are guided out of the interior of the
housing 102 to the outside between the two housing parts 102a and
102b.
Although our cells have been described in connection with specific
forms thereof, it will be appreciated that a wide variety of
equivalents may be substituted for the specified elements described
herein without departing from the spirit and scope of this
disclosure as described in the appended claims.
* * * * *